Production of films for projection of colors



April 26, 1932. A. OSWALD 1,855,198

N OF COLORS Filed Nov. 1, 1926 Patented Apr. 26, 1932 UNITED STATESPATENT OFFICE ane OSWALD, or rams, FRANCE, ASSIGNOR, BY ivrnsim NEWYORK, N. Y, A CORPORATION or DELA- DORIAN COLORFILM CORPORATION, OF WAREV PRODUCTION OF FILMS FOB ASSIGNMENTS, TO KELLER- PROJECTION OF COLORSApplication filed November 1, 1926, Serial No. 145,713, and in FranceNovember 16, 1925.

The object of this invention is to provide a method of impressing orembossing microscopic parallel lines and to gofler or crimp by means ofsuch treatment photographic and '5" motion picture films so as to obtaina reprovaries duction in natural colors.

The number of lines to be impressed in order to obtain a sufiicientlyfine and sufficiently sharp reproduction of such colors between 12 and35 lines per millimeter While films of the same kind hitherto used inthe trade hardly comprise more than 8 lines per millimeter.

I have discovered that the desired fine impressing or embossing isobtainable by the usual means, that is to say by means of highlyaccurate dividing machines as hereinafter described.

Such embossing can be made on plates or on cylinders and either inhollow or in relief. The lines may ofier a section either round orV-shaped, or rectangular or trapezoidal. The lines are parallelrespecting one another and arrangeable in any manner respecting theedges of the film. The embossing is intended for gofi'ering photographicor motion picture films, the surfaces of which are thereby transformedinto a multitude of tiny jur taposed lenses of substantiallyhemicylindri- P cal form.

Every one of these lenses will produce on the sensitized layer acomplete image of the main picture-taking objective. Any colorselectingfilter or screen designed to cause the said objective to appear ascolored. zones in the lines embossed or impressed on the film willtherefore enable the registration, at every point of the image, of thecolored radiations such as they will appear after passing through thefilter.

The path of light rays being reversible, those same films, used with aprojection apparatus similar to the picture-taking camera, willreconstitute the image in natural colors on the screen.

In the accompanying drawings, Figure l is a diagram indicating thepassage of the light rays through a film goifered in accordance with theinvention, and Fig. 2 is a fragmental diaphragm of the picture-takingobjectlve,

which zones or spaces will hereinafter be termed image zones.

Nith a certain aperture ofthe objective, if the goffering-i-s broadenough, that is to say if the number of microscopic lenses permillimeter of film as counted perpendicularly to the axis of the lenses,is small enough, or even if the zone a is large enough, the image zones2 will cover a restricted fraction of the surface corresponding to eachmicroscopic lens and the useful light appertaining to each said lenswill thus concentrate its effect on a more restricted surface, theresult being that the harmful effect of the light that passes throughthe spaces 25 separating the regions will have relatively lessinfluence. The unrinted zones N, which become dark when the film isdeveloped, will fill the dead spaces t. Of course this aperture of themicroscopic lenses Z respecting the aperture ofthe objective cannot beincreasedextremely far because the fraction of the total sensitizedsurface employed for the representation of the photographed objectis'thereby decreased.

But I have discovered that instead of using, as would at first sightseem indicated, an embossing producing ,microscopic lenses having anaperture corresponding to the aperture of the picture-taking objective,the proper thing is to use an embossing corresponding to a number oflenses per millimeter 10 to 40% less than the number corresponding tothe aperture of the picture-taking objective, Whether it be a case ofpicture-taking proper or a case of film reprinting. In other words, thezone a (Fig. 1) must be from 10 to 40% larger than zone a.

Goffering ofthe' films can be effected by pressing the plasticfilmdirectly against the embossed plate or cylinder M means of a presserroller of sufficient hardness, but then the given a straight sectionrepresenting exactly the profile which every one of the refracting linesof the film must have in "view of-the result aimed at. In recessed orembossed portions of the roller M or other impressing or embossingdevice, and r the radius of curvature of the hemispherical portions Zofthe film, thecurvature being such that the fo'ci of all the saidportions or lenses Z willzlie in the plane of the sensitized layer 9. p

I have discovered .thatfas concerns those refracting lines, to takeadvantage of the resiliency of the fi hn in order to obtain the requiredcurvatune of the hemicylindrical surfaces of the said film, :saidsurfaces contacting with the embossing deviceat their origin only andthenfreely developing within or insidethe embossed or recessed portionsof said em--. bossing-device under the influence of the superficialtension oflthe film which is ad justedI-by means of the pressure thatsaid fizhn receives and also by controllingits temperature and itshygrometric degree; The values of these three factors are determined,say,by pressing the'film against the embossing device bymeans of acounterdevice' provided with an adjustable'weight, by heating up to apredetermined and-constunt temperature eithertheembossing device er thecounter-device or the two of them, and lastly, by bringing the film toproper hygrometric condition through suitable drymg immediately previousto proceeding With I claim as my'invention: 7 1-.1A method of producingfilms for proection in colors, which comprlses embossing microscopicparallel lines from a recessed indentations than and not conforming tothe shape of the embossing to be produced.

4. "he process which comprises producing an embossed curved surface upona filinby pressure from a hardsurface carrying deeper indentationsfthan:the embossing to be pro- (Fig. 2 by lines employed have to be i ig. 2, Lindicates the carrying deepenin'dentations --boss ng to -b it is handierand simpler duced, thereby forming a hemicylindrical surface thereon.

5. The process which comprises producing an embossed curved surface upona film maintained relatively soft by heat and moisture, by pressure fromazhard surface carrying deeper indentations than the embossing to beproduced.

c6. Thefprocess which comprises produ ing an embossed .curvedsurfaceupon .acifilm maintained relatively soft by lieatfl and moisture, bypressure from a hard surface du d: h tGbrfO m hemicylindrical surfacethereon-- than the em-' a In testimony whereof I aflixmy signature.

ANDRE osWALD.

